Transmission mechanism



Aug. 19, 1941.; 1-. A. WETZEL.

TRANSMISSION MECHANISM 2 Sheets-Sheet 1 Filed April 24-, 1939 INVENTOYR Aug, 19, E941. T. A. WETZEI.

TRANSMISSION MECHANISM Filed April 24, 1939 2 Sheecs-Sheefqje Z Wu T 6 N W w m n pitch diameter is Patented at. 19,1941- UNITED STATES, PATENT OFFICE 2,253,357 TRANSMISSION MECHANISM Theodore'A. Wetzel, Milwaukee, Wis. Application April 24', 1939, Serial No. 269,62! 2 Claims. (01. 74-230.)

This invention relates to improvements in transmission mechanisms of the type employing belt and pulley or other. frictional gearing drive.

One of the objects of the presentinvention is to provide a transmission in which the ratio between the driver and driven elements thereof is automatically adjusted. This is accomplished by providing on driver and/or driven shafts pulleys automatically adjustable to alter their pitch diameter in response to varying conditions of speed and/r torque and .frictionally gearing such pulleys by an endless belt. v

Another object of the present invention is to provide a pulley comprised of .two sections axially adjustable to vary the pitch diameter of the pulley. x

Other objects and advantages reside in certain novel features of construction, arrangement, and combination of parts, which will be hereinafter more fully described and particularly pointed out in the appended claims, reference being had to the accompanying drawings forming a part of this specification, and in which:

.Figure 1 is a view in front elevation of a transmission mechanism embodying the invention and having pulleys in parallel multiple hookup, parts being shown in section for the sake of clarity;

Figure 2 is an endview of the mechanism shown in Figure 1; Y

Figure 3 is ,a view taken 3+3 ofFigure 1.

Broadly, the mechanism comprises V cross: section belts and pulleys; Each pulley is divided on the section line into two sections each with a cone-shaped, beltengaging surface. Each section, as positioned on the common shaft, has limited axial movement relative to the other. Increase or decrease of the spacing between these sections causes the belt to ride lower or higher in the V notch formed by the cone-shaped surfaces. In other words, the altered. By the use of wedge or screw means acting between the shaft and a section or sections of the pulley, this increase or decrease of spacing is accomplished. Any reactable energy storing member or spring'of predetermined strength, reacting-on the wedge or screw means, provides the means of automatically regulating the axial movement orchange in pitch diameter in response to changes in speed and/or torque conditions.

Various combinations or arrangements of these adjustable pitch diameter pulleys maybe made' to provide transmissions of varying characteristics in which the changes in the ratio of the *driver to the driven elements thereof will respond in such manner to changes in torque and/or speed .resulting from starting, increase or decrease in load or in power while running, runaway on driven element or brake applied on driver element, as will best suit the purpose desired. These arrangements will hereinafter be described in detail.

Throughout the specification the rotation of the various shafts and pulleys will be referred to as clockwise or counterclockwise, as

, viewed from the right of the drawings.

Multiple drive Referring now to the embodiment illustrated inFigures 1, 2, and 3, a plurality of sheaves or pulleys 3 are arranged in parallel fashion on common shafts in order that a greater load may be transferred. The sheaves or pulleys 3 are identical in construction, and the description thereof will-be applied to one only. The same is true of the driver and'driven shafts 1 and 2, with the exception that the energy-storing spring is coiled left-handedly in the shaft I and righthandedly in the driven shaft 2. With this construction it is important, when adjusting the sheaves for purposes of changing the pitch diameter, that they be adjusted in the, same degree. To accomplish this, the shaft 2 is provided, as shown, with three Spaced, raised, threaded portions 4. Co-extensive of the threaded portions 4 th shaft'is provided with a counterbore 5. Adjacent each threaded portion] opposed, arcuately extending slots 6 are provided in the wall of the shaft 2 extending between the counter-bore 5 and the lateral surface of the shaft 2. The surface of the shaft 2 in alinement with these slots 6 is provided with a circumferential groove I adapted to receive and rotatively retain a split collar 8. The pulley 3 is comprised of two sections, .each having acon'e-shaped, beltreceiving surface 9a--9b adapted, when the sections are placed in axial alinement, to provide a V-shaped belt-receiving groove. The section 3a of the pu1ley'3 has a central bore ID of sufficient diameter to permit the pulleys 3 to be placed on the shaft from one end thereof and to freely pass over the raised threaded portions ,4. Adjacent the bore i0 is a laterally extending flange ll adapted to fit over and retain the split co1-. lar 8.

A hollow closed end tube l2, substantially coextensive of the counter-bore 5, is positioned to,

be rotatively held therein. Within the tube I2 is provided innppositely spaced position and secure the split collar 8 to the section 3a. The fit between the split collar 8 and groove II is suflicient to maintain the section 3a. in accurate position on the shaft 2 while permitting the same torotate relatively thereto. The eirtended portion of the peg screws I5 is slidably retained in the radially extending slots 6 and fixedly engaged in the apertures I4 in the tube so that the section 31: rotates with th tube I2. This construction assures that each of the sections. 31; on the same shaft will rotate with respect thereto an identical amount to assure that the change in pitch diameter will be the same for each pulley on the same shaft. It also comprises stops limiting the relative movement between shaft andpulley.

The other section 3b is provided with a centrally located bore having a left-hand thread adapted to fit with the threaded portion 4 on the shaft 2. The fit is such as to permit relative rotation therebetween while maintaining the section 3b in proper aiinement with the shaft 2. Adjacent the hubs the sections 3a and 3b are provided with alined apertures spaced at 180. Peg screws II are threaded into the apertures in section 3b andhave extended portions slidably fitted within the alined apertures in section in. Thus, rotative force communicated to either of the sections will be transmitted to the other section while permitting them to have relative axial movement. The remaining constructionof the pulley 8, and the construction of the driving belt I8, is well known in the art, and is generally known under the term V-belt ive.

The coiled torsion spring I9L inthe tube in the driver shaft I is a left-hand spiral, while the spring I9R. in the tube of the'driven shaft 2 is right-hand spiral. ,In the position shown in Figure 1, the torsion springs I 9L and ISR in the shafts I and 2 have been wound to store energy as a result of an increase in torque due to starting or increase in load or power while running, and the pitch diameter of driver pulleys on shaft I has been decreased, and that of the driven pulleys on shaft 2 increased. In this position the shaft I has been rotated in a counterclockwise direction relative to the pulleys on said shaft an amount sufficient to cause the threads to move the sections apart, thereby permitting the belts to drop down to a smaller pitch diameter. Likewise, the pulleys 2 on the driven shaft -3 have been rotated counter clockwise relative to said shaft an amount'sumcient to cause the threads 4 to move the sections 3!; toward'the sections 311 so that the belt rides ona larger pitch diameter.

As torque or speed conditions vary the torsion.

springs 'wind or unwind to store or give up energy. As the torsion spring I91. givesup energy,

the pulleys on shaft I rotate counter clockwise relative to that shaft. As the torsion spring ISR gives up energy, the shaft 2 is rotateddyounter clockwise relative to g: pulleys I on that shaft. This causesthe sectio I to move together, and the sections 2b of pulleys on shaft 2 to move away from the sections to, thereby increasing the pitch diameter of the pulleys on shaft I and decreasing the pitch diameter of the pulleys on shaft 2.

of the pulleys on shaft shaft 2 is constituted the driver and is rotated in I The change in pitch diameter can effect an over drive relationship between the driver and driven shafts. The change in pitch diameters is effected when both driver and driven shafts are operated at'high as well as low rates of speed, as such change is responsive .to increment changes in speed and/or torque conditions. It is possible that at times the pitch diameters of the driver and-driven pulleys will be constantly changing in minute degrees. v I

The transmission may be effectively used for braking purposes. In this connection the driven a clockwise direction. The driver shaft I is constituted the driven shaft and thebrake 20 is applied to it. When the brake is not applied, the driven shaft, which will then constitute the brake drum, revolves at a slow rate of speed with respectto the driving shaft. When the brake is applied,-consequentially increased torque causes an decrease in pitch diameter of the pulleys on the drum shaft and an increase in pitch diameter of the pulleys on the newly constituted driver shaft. This ratio change causes the brake drum to be driven at a greater rate -6f speed than the drivingshaft, and by reason thereof the braking will be accomplished in a smooth and effective fashion.

- The braking can also be applied to the driver shaft. In such instance the shaft 2 is constituted the driver and rotated clockwise. The shaft drives the pulleys through engagement between the end of the slot 6 and the peg screws I5. The torsion spring I9R is wound left-hand spiral and continually urges the pulley counterclockwise of the shaft 2 to maintain the aforesaid driving.

engagement. In this position the sections 3a. and

3b are; together, and a large pitch diameter 1 created. The torsion spring ISL in shaft I, which will be constituted the driven shaft, is wound right-hand spiral. From this it will be understood that the pulley on shaft I is urged clockwise thereof into driving engagement with the shaft at the limit permitted and with the pitch diameter at its smallest size. When a brake is applied to the driver shaft 2, the reaction force is partly used in winding the torsion springs to cause the pitch diameter of the driver to decrease and the pitch diameter of the driven to increase, thus multiplying the braking power inherent in the driving mechanism.

Double action The reactable energy-storingspring-may also be made-to have a double action. The torsion and give up energy as they unwind. They are not suitable, however, to store energy. upon being unwound more than their normal unstressed or repose position. In order to have a pulley that will decrease its pitch diameter from. normal upon an increase in torque requirement acting in one direction, and increase its pitch diameter from normal upon an increase in torque requirement act ing in another direction, it is essential to construct the energy storing spring in such a manner as to make it double acting.

. This can be accomplished by providing in addition to the torsion spring IBR, disclosed in Figure I, a similar torsion spring having opposing reaction. To provide for this additional spring it would merely necessitate extending the shaft 2 and tube I2 an amount sufiicient to accommodate the additional spring and capping the end of the shaft as extended to form an anchor for the outer end of the spring. The inner end would be secured to the tube II in like manner as spring ISR. In this construction the added spring would also be right-hand spiral as when placed in end to end relationship and wound by a common member (the tube 12) attached to adjacent ends springs of the same spiral winding react against each other. v 1 v The opposing springsare so adjusted relative to each other and'the shaft that under normal operating conditions the pulley is adjusted for a pitch diameter intermediate between its smallest I said member to regulate the'shifting.

' 2. A multiple sheave adjusting pulley comprising a shaft, a plurality of spaced threaded portions on said shaft, a counter bore in said shaft coextensive of said portions, a plurality of arcuately extending slots in said shaft between said bore and the lateral surface of said shaft,

a tube rotatably supported in said bore, a coil spring within said tube and connected thereto and to said shaft, a plurality of sheaves each comprising two sections, said sections forming therebetween a -V-shaped belt-receiving groove, one of said sections of each pulley being rotatively mounted on said shaft, means connecting each of said sections to said tube, said means operating through said slots, the other of said sections of each-pulley having a threaded interconnection with one of said threaded'jportions, and means connecting said sections of each sheave restraining them to rotate simultaneously 'while permit- 20 ting them to have relative axial movement.

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